1. Field of the Invention
This invention relates to arming and firing devices in which a pyrotechnic or explosive output charge is actuated on command to initiate a reactive process, such as combustion in a rocket motor, or to energize an apparatus, such as a piston-operated mechanism. More particularly, it relates to devices of this type incorporating means for preventing accidental or inadvertent actuation of the output charge. Still more particularly, it concerns arming and firing devices for rocket motors adapted to prevent the passage, by blow-by or leakage, of contaminating solid or gaseous rocket combustion products.
2. Prior Art
Safety fuses and other arming and firing devices employing explosive or pyrotechnic charges to initiate rocket motors, activiate explosive charges, actuate quick-release mechanisms and perform similar tasks are well known. Commonly such devices incorporate safety features designed to prevent premature firing. Some of these employ means for structurally completing a mechanical or chemical firing train in response to an arming command. Others rely on means for closing an electrical firing circuit. Still others utilize both structural and electrical arming means.
Generally, these prior art devices tend to be undesirably large and complex. Additionally, such devices are frequently exposed to environmental or operational conditions which require them to be sealed to prevent the passage of contaminants. By way of example, arming and firing devices for internal use in rocket-propelled guided missiles must be constructed to prevent the blow-by or leakage of rocket combustion products which would be harmful to the missile's guidance and firing systems. Conventionally, seals and O-rings are employed for this purpose. Devices relying on these, however, are difficult and costly to manufacture and are subject to unpredictable failure.
Recent advances in through-bulkhead initiation technology have led to the development of leak-proof firing devices. The construction of these devices, however, does not lend itself readily to the application of prior art safe-arm means for preventing their accidental or inadvertent firing.